The plant kava-kava (piper methysticum Forst. Piperaceae) is native to Polynesia. An intoxicating beverage made from its crushed roots has been used in ceremonies since ancient times.
Kava-kava has been found to have significant analgesic and anesthetic effects via non-opiate pathways. It also can be used as phytotranquilizer to reduce nervousness and overexcitement. However, kava-kava's most popular application is as a natural anxiolytic and has compared favorably to a number prescription medications such as benzodiazepines. Kava-kava's pharmacological activity has been attributed to lactones present in the plant roots.
Several kava-kava products are available, such as kava-kava-based beverages, kava-kava ethanol extract solutions, kava-kava emulsions with glycerin and coconuts oil dispersed in water, and kava-kava extract tablets. Unfortunately, the active lactones in kava-kava-based products have low bioavailability since the lactones themselves are practically insoluble in water. For example, the maximum solubility of kawain at 21.degree. C. is about 2.2 mg/100 ml water. Accordingly, high doses of kava-kava-based products or the active lactones are required to obtain therapeutic effects.